Kinetic manifestations of low-temperature combustion of hydrocarbons and hydrogen: Cool and intermittent flames

Phenomena inherent in degenerate branched and completely branched chain reactions are considered from a unified viewpoint. In the case of degenerate branched chain reactions, such phenomena include a negative temperature coefficient, cool flames, and oscillations arising in slow combustion of hydrocarbons. Another phenomenon (intermittent flames) is inherent only in completely branched chain reaction of low-temperature combustion of hydrogen at reduced pressures in the presence of SO$_2$ additives. These kinetic manifestations of chain branching processes are characterized by a variety of elementary reactions with participation of intermediate compounds and free radicals with different structures. A specific kinetic feature of reactions of both types is simultaneous participation of the active center responsible for chain branching in the branched reaction and in the reaction of propagation of an ordinary chain.